<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
// +----------------------------------------------------------------------
// | Copyright (c) 2009 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

/**
 * Base64 加密实现类
 * @category   ORG
 * @package  ORG
 * @subpackage  Crypt
 * @author    liu21st <liu21st@gmail.com>
 */
class Base64 {

	/**
	 * 加密字符串
	 * @access static
	 * @param string $str 字符串
	 * @param string $key 加密key
	 * @return string
	 */
	public static function encrypt($data,$key) {
		$key    =   md5($key);
		$data   =   base64_encode($data);
		$x=0;
		$len = strlen($data);
		$l = strlen($key);
		for ($i=0;$i< $len;$i++) {
			if ($x== $l) $x=0;
			$char   .=substr($key,$x,1);
			$x++;
		}
		for ($i=0;$i< $len;$i++) {
			$str    .=chr(ord(substr($data,$i,1))+(ord(substr($char,$i,1)))%256);
		}
		return $str;
	}

	/**
	 * 解密字符串
	 * @access static
	 * @param string $str 字符串
	 * @param string $key 加密key
	 * @return string
	 */
	public static function decrypt($data,$key) {
		$key    =   md5($key);
		$x=0;
		$len = strlen($data);
		$l = strlen($key);
		for ($i=0;$i< $len;$i++) {
			if ($x== $l) $x=0;
			$char   .=substr($key,$x,1);
			$x++;
		}
		for ($i=0;$i< $len;$i++) {
			if (ord(substr($data,$i,1))<ord(substr($char,$i,1))) {
				$str    .=chr((ord(substr($data,$i,1))+256)-ord(substr($char,$i,1)));
			}else{
				$str    .=chr(ord(substr($data,$i,1))-ord(substr($char,$i,1)));
			}
		}
		return base64_decode($str);
	}
}